First, the artist should be the sole originator and producer of the image.
Second, the number of pieces in the edition does not exceed 1000 world-wide.
Third, the image should be on acid-free (archival) museum paper with permanent color pigments, to prevent fading, yellowing and deterioration for an approximate life of 400 years.
Fourth, the artist personally hand- signs, numbers and titles each piece separately. not stamped or printed.
Finally, nothing beyond the following proofs should exist:
Artist proofs = Not to exceed 1% of the edition number.
Printer's proof = One referenced and retained by printer.
Cancellation proof = One showing that the stones or plates were destroyed.
Trial proofs = Those examined by the artist prior to birth of the edition.
Remarques = Where the artist does a drawing or small painting related to the image in the surrounding blank margin. They should not exceed 2% of the edition.
NOTE: If other forms of proofs exist, buyer beware!
FINALLY: In an effort to generate large profits at the expense of the public, some producers have developed what is called "The Time Limited Edition." This is where a time pressure frame is established with a production cut-off date, after which no more orders are taken. The producer infers or implies that the work is going to become valuable so... you better place your order. The final number can be in the thousands, making each no more valuable on the market than the cost of each separate piece of paper!
REMEMBER... a true limited edition doesn't exceed 1000 pieces world-wide, with the edition number established by the artist (originator) before it is created.